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• How do you write byte[] array using log4.net

  - by like.no.other

  Hi, I have a byte[] with some data in it, I would like to write this byte array AS-IS to the log file using log4.net. The problems that i am facing is that There are no overload for byte[] in TextWriter, so even implementing an IObjectRenderer is of no use. I dont have access to the underlying Stream object of Log4.net Also tried converting byte[] into char[] still when i write it, it adds an extra byte. Is this even possible with Log4.net. Thanx in Advance.

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• How to ensure that no non-ascii unicode characters are entered ?

  - by Jacques René Mesrine

  Given a java.lang.String instance, I want to verify that it doesn't contain any unicode characters that are not ASCII alphanumerics. e.g. The string should be limited to [A-Za-z0-9.]. What I'm doing now is something very inefficient: import org.apache.commons.lang.CharUtils; String s = ...; char[] ch = s.toCharArray(); for( int i=0; i<ch.length; i++) { if( ! CharUtils.isAsciiAlphanumeric( ch[ i ] ) throw new InvalidInput( ch[i] + " is invalid" ); } Is there a better way to solve this ?

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• [C++] instantiating bitset using hex character.

  - by bndz

  Hey, I'm trying to figure out how to instantiate a 4 bit bitset based on a hex character. For instance, If I have a character with value 'F', I want to create a bitset of size 4 initialized to 1111 or if it is A, i want to initialize it to 1010. I could use a bunch of if statements like so: fn(char c) { bitset<4 temp; if(c == 'F') temp.set(); //... if(c == '9') { temp.set(1); temp.set(3); } //... } This isn't efficient, is there a way of easily converting the string to a decimal integer and constructing the bitset using the last 4 bits of the int? Thanks for any help.

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• Puzzle: Overload a C++ function according to the return value

  - by Motti

  We all know that you can overload a function according to the parameters: int mul(int i, int j) { return i*j; } std::string mul(char c, int n) { return std::string(n, c); } Can you overload a function according to the return value? Define a function that returns different things according to how the return value is used: int n = mul(6, 3); // n = 18 std::string s = mul(6, 3); // s = "666" // Note that both invocations take the exact same parameters (same types) You can assume the first parameter is between 0-9, no need to verify the input or have any error handling.

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• Pass 2d array to function in C?

  - by Evelyn

  I know it's simple, but I can't seem to make this work. My function is like so: int GefMain(int array[][5]) { //do stuff return 1; } In my main: int GefMain(int array[][5]); int main(void) { int array[1800][5]; GefMain(array); return 0; } I referred to this helpful resource, but I am still getting the error "warning: passing argument 1 of GefMain from incompatible pointer type." What am I doing wrong?

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• deleting dublicates in listview delphi

  - by radick

  hi all I am trying to remove dublicates in my listview my function like this below procedure RemoveDuplicates(const LV:TbsSkinListView); var i,j: Integer; begin LV.Items.BeginUpdate; LV.SortType := stText; try for i := 0 to LV.Items.Count-1 do begin for j:=i+1 to LV.Items.Count-1 do begin if SameText(LV.Items[i].SubItems[0], LV.Items[j].SubItems[0]) and SameText(LV.Items[i].SubItems[1], LV.Items[j].SubItems[1]) and SameText(LV.Items[i].SubItems[2], LV.Items[j].SubItems[2]) and SameText(LV.Items[i].SubItems[3], LV.Items[j].SubItems[3]) then LV.Items.Delete(j); end; end; finally LV.SortType := stNone; LV.Items.EndUpdate; end; ShowMessage('Deleted'); end; but its not doing what i intended can anyone help me ?

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• Does replacing statements by expressions using the C++ comma operator could allow more compiler opti

  - by Gabriel Cuvillier

  The C++ comma operator is used to chain individual expressions, yielding the value of the last executed expression as the result. For example the skeleton code (6 statements, 6 expressions): step1; step2; if (condition) step3; return step4; else return step5; May be rewritten to: (1 statement, 6 expressions) return step1, step2, condition? step3, step4 : step5; I noticed that it is not possible to perform step-by-step debugging of such code, as the expression chain seems to be executed as a whole. Does it means that the compiler is able to perform special optimizations which are not possible with the traditional statement approach (specially if the steps are const or inline)? Note: I'm not talking about the coding style merit of that way of expressing sequence of expressions! Just about the possible optimisations allowed by replacing statements by expressions.

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• Retrieving datatypes from underlying database

  - by H4mm3rHead

  Hi, Im making an application that displays information about an underlying database. The database can be anything, but is typically either Oracle, MSSQL or MySQL. I am trying to extract the datatype but cannot seem to get this right. I have a DbConnection because i dont know whether I need a OleDbConnection or an OdbcConnection. On this connection I make a GetSchema("Columns", "mytablename") query and gets the result back. It seems though that there are some inconsistencies with my datatypes or the query returns different datatypes for the different databases. For instance, in my MSSQL database I query and get an integer back (which seems to be the OleDbType) which I map to a datatype. My varchars is now of type char - no length - and this confuses me a bit. I guess my main question is something like: Is there any way of making a uniform way of extracting datatypes across providers and having an "accurate" representation of the datatype?

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• iSightAudio.plugin error when playing video using MediaPlayer

  - by Elisabeth

  I am working on creating a simple iPhone app that plays a movie via URL. When I Build&Run to test in the simulator, it works fine; as soon as I start playing the movie, I get the following message in the console: [1757:4b03] Cannot find executable for CFBundle/CFPlugIn 0x820ffe0 </Library/Audio/Plug-Ins/HAL/iSightAudio.plugin> (not loaded) [1757:4b03] Cannot find function pointer iSightAudioNewPlugIn for factory 9BE7661E-8AEF-11D7-8692-000A959F49B0 in CFBundle/CFPlugIn 0x820ffe0 </Library/Audio/Plug-Ins/HAL/iSightAudio.plugin> (not loaded) I don't get this error on other programs, so I assume it has something to do with this specific program, which uses the MediaPlayer.framework. Does anyone know what is causing this problem and how to fix it? Thank you

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• IO completion port key confusion

  - by Richard Tew

  I'm writing an IO completion port based server (source code here) using the Windows DLL API in Python using the ctypes module. But this is a pretty direct usage of the API and this question is directed at those who have a knowledge of IOCP, not Python. As I understand the documentation for CreateIoCompletionPort, you specify your "user defined" completion key when you call this function with a file handle (in my case a socket) you are associating with the created IOCP. When you get around to calling GetQueuedCompletionStatus, you get a completion key value along with a pointer to an overlapped object. The completion key should identify what overlapped object and request has completed. However, let's say I pass in 100 as the completion key in my CreateIoCompletionPort call with an overlapped object. When the same overlapped object has its IO completed and it arrives back through GetQueuedCompletionStatus, the completion key that accompanies it is much larger and bares no resemblance to the original value of 100. Am I misunderstanding how the completion key works, or must I be doing it wrong in the source code I linked above?

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• Objective c key path operators @avg,@max .....

  - by davide

  arr = [[NSMutableArray alloc]init]; [arr addObject:[NSNumber numberWithInt:4]]; [arr addObject:[NSNumber numberWithInt:45]]; [arr addObject:[NSNumber numberWithInt:23]]; [arr addObject:[NSNumber numberWithInt:12]]; NSLog(@"The avg = %@", [arr valueForKeyPath:@"@avg.intValue"]); This code works fine, but why? valueForKeyPath:@"@avg.intValue" is requesting (int) from each NSNumber, but we are outputting a %@ string in the log. If i try to output a decimal %d i get a number that possibly is a pointer to something. Can somebody explain why the integers become NSNumbers when i call the @avg operator?

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• Are there any Python reference counting/garbage collection gotchas when dealing with C code?

  - by Jason Baker

  Just for the sheer heck of it, I've decided to create a Scheme binding to libpython so you can embed Python in Scheme programs. I'm already able to call into Python's C API, but I haven't really thought about memory management. The way mzscheme's FFI works is that I can call a function, and if that function returns a pointer to a PyObject, then I can have it automatically increment the reference count. Then, I can register a finalizer that will decrement the reference count when the Scheme object gets garbage collected. I've looked at the documentation for reference counting, and don't see any problems with this at first glance (although it may be sub-optimal in some cases). Are there any gotchas I'm missing? Also, I'm having trouble making heads or tails of the cyclic garbage collector documentation. What things will I need to bear in mind here? In particular, how do I make Python aware that I have a reference to something so it doesn't collect it while I'm still using it?

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• llvm clang struct creating functions on the fly

  - by anon

  I'm using LLVM-clang on Linux. Suppose in foo.cpp I have: struct Foo { int x, y; }; How can I create a function "magic" such that: typedef (Foo) SomeFunc(Foo a, Foo b); SomeFunc func = magic("struct Foo { int x, y; };"); so that: func(SomeFunc a, SomeFunc b); // returns a.x + b.y; ? Note: So basically, "magic" needs to take a char*, have LLVM parse it to get how C++ lays out the struct, then create a function on the fly that returns a.x + b.y; Thanks!

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• How do I draw an arrow on a histogram drawn using ggplot2?

  - by jon

  Here is dataset: set.seed(123) myd <- data.frame (class = rep(1:4, each = 100), yvar = rnorm(400, 50,30)) require(ggplot2) m <- ggplot(myd, aes(x = yvar)) p <- m + geom_histogram(colour = "grey40", fill = "grey40", binwidth = 10) + facet_wrap(~class) + theme_bw( ) p + opts(panel.margin=unit(0 ,"lines")) I want to add labels to bars which each subject class fall into and produce something like the post-powerpoint processed graph. Is there way to do this within R ? ...... Edit: we can think of different pointer such as dot or error bar, if arrow is not impossible Let's say the following is subjects to be labelled: class name yvar 2 subject4 104.0 3 subject3 8.5 3 subject1 80.0 4 subject2 40.0 4 subject1 115.0 classd <- data.frame (class = c(2,3,3,4,4), name = c ("subject4", "subject3", "subject1", "subject2", "subject1"), yvar = c(104.0, 8.5,80.0,40.0, 115.0))

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• Convert CString to string (VC6)

  - by Yan Cheng CHEOK

  I want to convert CString to string. (Yup. I know what am I doing. I know the returned string will be incorrect, if CString value range is outside ANSI, but That's Is OK!) The following code will work under VC2008. std::string Utils::CString2String(const CString& cString) { // Convert a TCHAR string to a LPCSTR CT2CA pszConvertedAnsiString (cString); // construct a std::string using the LPCSTR input std::string strStd (pszConvertedAnsiString); return strStd; } But VC6 doesn't have CT2CA macro. How I can make the code to work as well in both VC6 and VC2008?

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• Assigning a view controller to be the delegate of a subview which is not directly descendent?

  - by ambertch

  I am writing an iphone app where in numerous cases a subview needs to talk to its superview. For example: View A has a table view that contains photos A has a subview B which allows users to add photos, upon which I want to auto append them to A's table view So far I have been creating a @protocol in B, and registering A as the delegate. The problem in my case is that B has a subview C that allows users to add content, and I want actions in C to invoke changes in its grandparent, A. Currently I am working around this by passing around a self pointer to my base view controller (C.delegate = B.delegate), but it doesn't seem very proper to me. Any thoughts? (and/or general advice on code organization when all sort of subviews needs to talk to superviews would be greatly appreciated) Thanks!

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• c++ library for endian-aware reading of raw file stream metadata?

  - by Kache4

  I've got raw data streams from image files, like: vector<char> rawData(fileSize); ifstream inFile("image.jpg"); inFile.read(&rawData[0]); I want to parse the headers of different image formats for height and width. Is there a portable library that can can read ints, longs, shorts, etc. from the buffer/stream, converting for endianess as specified? I'd like to be able to do something like: short x = rawData.readLeShort(offset); or long y = rawData.readBeLong(offset) An even better option would be a lightweight & portable image metadata library (without the extra weight of an image manipulation library) that can work on raw image data. I've found that Exif libraries out there don't support png and gif.

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• Put logic behind generated LinqToSql fields

  - by boris callens

  In a database I use throughout several projects, there is a field that should actually be a boolean but is for reasons nobody can explain to me a field duplicated over two tables where one time it is a char ('Y'/'N') and one time an int (1/0). When I generate a datacontext with LinqToSql the fields off course gets these datatypes. It would be nice if I don't have to drag this stupid choice of datatype throughout the rest of my application. Is there a way to give the generated classes a little bit of logic that just return me return this.equals('Y'); and return this==1; Preferably without having to make an EXTRA field in my partial class. It would be a solution to give the generated field a totally different name that can only be accessed through the partial class and then generate the extra field with the original name with my custom logic in the partial class. I don't know how to alter the accesibility level in my generated class though.. Any suggestions?

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• Counting characters in an Access database column using SQL

  - by jzr

  I have the following table col1 col2 col3 col4 ==== ==== ==== ===== 1233 4566 ABCD CDEF 1233 4566 ACD1 CDEF 1233 4566 D1AF CDEF I need to count the characters in col3, so from the data in the previous table it would be: char count ==== ===== A 3 B 1 C 2 D 3 F 1 1 2 Is this possible to achieve by using SQL only? At the moment I am thinking of passing a parameter in to SQL query and count the characters one by one and then sum, however I did not start the VBA part yet, and frankly wouldn't want to do that. This is my query at the moment: PARAMETERS X Long; SELECT First(Mid(TABLE.col3,X,1)) AS [col3 Field], Count(Mid(TABLE.col3,X,1)) AS Dcount FROM TEST GROUP BY Mid(TABLE.col3,X,1) HAVING (((Count(Mid([TABLE].[col3],[X],1)))>=1)); Ideas and help are much appreciated, as I don't usually work with Access and SQL.

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• C# SendMessage to C++ WinProc

  - by jws

  I need to send a string from C# to a C++ WindowProc. There are a number of related questions on SO related to this, but none of the answers have worked for me. Here's the situation: PInvoke: [DllImport("user32", CharSet = CharSet.Auto)] public extern static int SendMessage(IntPtr hWnd, uint wMsg, IntPtr wParam, string lParam); C#: string lparam = "abc"; NativeMethods.User32.SendMessage(handle, ConnectMsg, IntPtr.Zero, lparam); C++: API LRESULT CALLBACK HookProc (int code, WPARAM wParam, LPARAM lParam) { if (code >= 0) { CWPSTRUCT* cwp = (CWPSTRUCT*)lParam; ... (LPWSTR)cwp->lParam <-- BadPtr ... } return ::CallNextHookEx(0, code, wParam, lParam); } I've tried a number of different things, Marshalling the string as LPStr, LPWStr, also tried creating an IntPtr from unmanaged memory, and writing to it with Marshal.WriteByte. The pointer is the correct memory location on the C++ side, but the data isn't there. What am I missing?

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• gcc, UTF-8 and limits.h

  - by bobby

  My OS is Debian, my default locale is UTF-8 and my compiler is gcc. By default CHAR_BIT in limits.h is 8 which is ok for ASCII because in ASCII 1 char = 8 bits. But since I am using UTF-8, chars can be up to 32 bits which contradicts the CHAR_BIT default value of 8. If I modify CHAR_BIT to 32 in limits.h to better suit UTF-8, what do I have to do in order for this new value to come into effect ? I guess I have to recompile gcc ? Do I have to recompile the linux kernel ? What about the default installed Debian packages, will they work ?

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• Is Boost.Tuple compatible with C++0x variadic templates ?

  - by Thomas Petit

  Hi, I was playing around with variadic templates (gcc 4.5) and hit this problem : template <typename... Args> boost::tuple<Args...> my_make_tuple(Args... args) { return boost::tuple<Args...>(args...); } int main (void) { boost::tuple<int, char> t = my_make_tuple(8, 'c'); } GCC error message : sorry, unimplemented: cannot expand 'Arg ...' into a fixed-length argument list In function 'int my_make_tuple(Arg ...)' If I replace every occurrence of boost::tuple by std::tuple, it compiles fine. Is there a problem in boost tuple implementation ? Or is this a gcc bug ? I must stick with Boost.Tuple for now. Do you know any workaround ? Thanks.

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• Get the lua command when a c function is called

  - by gamernb

  Supposed I register many different function names in Lua to the same function in C. Now, everytime my C function is called, is there a way to determine which function name was invoked? for example: int runCommand(lua_State *lua) { const char *name = // getFunctionName(lua) ? how would I do this part for(int i = 0; i < functions.size; i++) if(functions[i].name == name) functions[i].Call() } int main() { ... lua_register(lua, "delay", runCommand); lua_register(lua, "execute", runCommand); lua_register(lua, "loadPlugin", runCommand); lua_register(lua, "loadModule", runCommand); lua_register(lua, "delay", runCommand); } So, how do I get the name of what ever function called it?

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• Typical text encoding and EOL behavior on mobile devices

  - by Dan W

  Typical things to worry about when dealing with text are the BOM/signature, encoding, and the end of line (EOL) char/chars. I know that Windows often favours \r\n (CR+LF) and Mac/Linux favours \n (LF), but how about popular mobile devices such as the iPhone and Android? Do typical apps on those platforms favour one or the other (or maybe even \r for iOS)? I'll supply both types to the user just in case, but I'd like to choose one as default. Also, which text encodings are mobiles most likely to use - UTF-8, iso-8859-1, Windows 1252 (or other default codepage) or maybe even UTF-16? And if they use UTF-8/16, are they likely to need (or require not having) a BOM/signature? What is the typical behavior here? Once again, I'll supply a range of encodings to the user just in case, but I'd like to prioritize or use certain encodings as default if it's appropriate.

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• difference fixed width strings and zero-terminated strings

  - by robUK

  Hello, gcc 4.4.4 c89 I got into a recent discussion about "fixed width strings" and "zero terminated strings". When I think about this. They seem to be the same thing. A string with a terminating null. i.e. char *name = "Joe bloggs"; Is a fixed width string that cannot be changed. And also has a terminating null. Also in the discussion I was told that strncpy should never been used on 'zero terminated strings'. Many thanks for any susgestions,

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